The present invention relates to a pressure container and a method for manufacturing and filling a pressure container. The pressurized package has an outer container and an inner container within the outer container. In the outer container a chamber for material to be dispensed is arranged and in the inner container a propellant chamber for propellant is arranged, which are separated from each other in a manner that is impermeable to liquid and gas. The outer container is closed by a cover part on which a valve part is arranged for dispensing the material from the chamber outwards. To improve pressurized packages of this type, a pressurized cartridge containing a propellant is arranged in the inner container, and the pressurized cartridge is associated with an opening mechanism for at least one-time opening of the pressurized cartridge to the propellant chamber of the inner container. The opening mechanism reacts to filling of the chamber with material to be dispensed.
This type of container is used, for example, in gas operated setting tools, wherein they contain a dispensable fuel.
Liquid hydrocarbons stored in the pressure containers is used to drive the aforementioned setting tools. The replaceable pressure containers or gas bottles are equipped with a dosing head, which is fastened onto the gas bottle by means of a snap-on connection. The pressure container/gas bottle and dosing head system is then introduced into the setting tool.
In the case of the pressure container, it is desirable that there is no penetration of propellant into the material to be dispensed chamber and that there is no escape of propellant or material to be dispensed into the environment. It is also desirable to attain a maximum fill volume of material to be dispensed or fuel in the pressure container.
U.S. Pat. No. 5,069,590 discloses a pressure container, wherein an inner thin-walled metal container, in particular one made of aluminum, is arranged in an external, thick-walled container (e.g., likewise made of aluminum). At the opening of the pressure container, the two containers are rolled onto each other, whereby the opening is closed with a cover part, in which a valve is arranged. When this is done, the material to be dispensed is arranged inside the inner container, while the propellant is arranged in the outer container. In this case, the propellant is introduced into the outer container through a rubber stopper arranged in the floor of the pressure container, in that the rubber stopper is perforated using a needle. The drawback here is that when acceleration forces act upon the pressure container, the inner container, because of the relatively large fill volume with material to be dispensed, is heavily mechanically stressed. Furthermore, there can be a loss of propellant from the outer container at the rolled flanged edge. The ratio of propellant to medium to be dispensed in the case of fuel—pressurized packages for setting tools is approx. 5/40 (e.g. 5 g/40 g). Particularly in longer periods of storage, therefore, with a loss of 3–4 g of propellant/year, the pressurized package can become unusable in virtue of the loss of propellant.
It is therefore advantageous if the propellant is arranged in the inner container, because a loss of material to be dispensed or fuel, affects the operation of the pressurized package less seriously than a loss of propellant.
U.S. Pat. No. 4,360,131 discloses a pressurized package, wherein the propellant is arranged in an inner container and the material to be dispensed is in an outer container. The inner container is sealed and contains a propellant, which comprises at least two constituents. After the lapse of a pre-determined interval of time after manufacturing and filling of the pressurized package, the formation of the propellant is done by combining its constituents. The advantage in this instance is that there is no connection favoring diffusion between the inner container and the valve.
The drawback in this instance is the use of a propellant comprised of two or more constituents, which results in relatively high manufacturing costs. It is difficult to generate a propellant pressure that is sufficient to maintain a gaseous fuel in the pressurized package completely in its liquid phase at ambient pressure and temperature.